The present invention relates to a process for a spinning arrangement for dealing with the correction of an end break in this arrangement, during operation of which sliver-like fiber material fed to the spinning arrangement is opened to single fibers by means of an opening roller, the single fibers are transferred in the form of a fiber veil to a suctioned collecting surface, which is driven in the direction of motion of the single fibers, the fiber veil is condensed to a narrow fiber strand on the collecting surface and the condensed fiber strand is spun to a yarn downstream of a nipping line by means of a twisting nozzle.
A spinning arrangement of the type mentioned is prior art in U.S. Pat. No, 6,058,693. This arrangement functions with a suctioned opening roller, which transfers the single fibers at a relatively low speed and in the form of a fiber veil to a somewhat faster rotating collecting surface, the suction opening arranged thereto tapering in the direction of motion of the collecting surface to such a degree that the single fibers are laterally displaced and the original fiber veil is condensed to a roving-like fiber strand. The condensing process is at an end at the latest at the nipping line and downstream thereof, the fiber strand is imparted a spinning twist by means of a twist nozzle for the production of the yarn. The nipping line acts hereby as a twist block. A yarn is produced which has similar characteristics to yarns produced in so-called airjet spinning, although the drafting unit typical for airjet spinning is not present in this case.
When an end-break occurs in such a spinning arrangement, the interrupted spinning process must be started up again by a piecing process. The known publication does not disclose how the spinning arrangement is operated in the case of an end-break.
It is an object of the present invention to show some possible methods for operating the known spinning arrangement in the case of an end-break. In further embodiments, variations of the piecing process will be shown below.
This object has been achieved in accordance with the present invention in that, in the event of an end-break, the feeding of the fiber material is interrupted and the fiber strand is suctioned in the area of the nipping line until the collecting surface is free of single fibers.
The interruption of the material feed, which is known per se in open-end rotor spinning, is a practical way of preventing the continued feeding of opened single fibers in the form of a fiber veil to the collecting surface, which fibers cannot be subsequently withdrawn. The suctioning of the single fibers and the clearing of the collecting surface serves to avoid further complications during a piecing operation. For the suction, a suction tube can be provided, which can be located upstream or downstream of the nipping line in the direction of motion of the fiber material. A suction tube can either be present at each spinning station or can be placed there by a maintenance arrangement when required. It is, however, practical when a suction tube is arranged to each individual spinning arrangement, which suction tube can be automatically applied to the collecting surface and activated in the case of an end-break.
Subsequently to the carrying out of the preparation as described above, the spinning arrangement can be set in operation again, whereby there are many possible variations for the piecing process.
In a first process to set the spinning arrangement in operation again, the fiber material feed is set in motion again and subsequently the fiber strand is fed by means of the collecting surface and for a given time is again suctioned in the area of the nipping line; the suction is de-activated in order for the fiber strand to be transferred to the twist nozzle. This ensures that when the spinning arrangement is set in operation again, an operational state exists firstly on the collecting surface, in which state the number of the single fibers transported by the collecting surface is known. Only when this state has been achieved is the condensed fiber strand transferred to the twist nozzle.
In a second variation of a process it is provided that after the suction of the fiber strand the drive of the collecting surface is interrupted and subsequently a piecing yarn is drawn backwards—in the opposite direction to the operational delivery direction—through the twist nozzle into the area of the opening roller, where it is disposed on the collecting surface, whereby, in order to set the spinning arrangement in operation again, the fiber material feed is set in motion again and the drive of the collecting surface is taken up again. In this variation, the piecing yarn is already threaded or guided into the twist nozzle, it simply must be guided back into the area of the opening roller. The piecing yarn can come from the winder of the relevant spinning arrangement or it can come from an auxiliary winder which is only used for piecing. The length of the piecing yarn should have a length which can always be reproduced. It is practical in this case to bring the collecting surface to a standstill. Only when the spinning arrangement is set in operation again, is the last end of the piecing yarn disposed onto the collecting surface, namely as soon as the new fiber veil is formed on the collecting surface. In order to feed the piecing yarn back into the area of the opening roller, an auxiliary nozzle is advantageously used which can be applied thereto. In a third piecing process it is provided that subsequent to the suction of the fiber strand, while the collecting surface temporarily rotates in the opposite direction to the operational direction of motion, a piecing yarn is threaded backwards—in the opposite direction to the operational delivery direction-through the twist nozzle to the area of the opening roller, whereby in order to start up the spinning arrangement, the fiber material feed and the drive of the collecting surface in operational direction of motion are all re-activated. The piecing yarn, as in the previously described variation, is already threaded through the twist nozzle, but is transported by the temporarily reversely rotating collecting surface to the area of the opening roller. If required, it could be provided here that the collecting surface together with the suction device arranged thereto be swivelled away a little from the opening roller. As soon as the end of the piecing yarn reaches the area of the opening roller, the fiber material feed can be continued, whereby the collecting surface is driven in its normal operational direction of motion.
These and further objects, features and advantages of the present invention will become more readily apparent from the following detailed description thereof when taken in conjunction with the accompanying drawings.